Conventionally, multilayered structures including a layer made of polyolefin, such as polyethylene and polypropylene, and a layer made of a saponified ethylene-vinyl acetate copolymer (hereinafter, may be abbreviated as an EVOH) excellent in barrier properties are widely used for various applications, particularly such as food packaging containers and fuel containers, taking advantage of their barrier properties. Such a multilayered structure is used as various molded products, such as a film, a sheet, a cup, a tray, and a bottle. At this time, there is a case that chips, defective products, and the like generated when obtaining the various molded products are collected and melt molded to be reused as at least one layer of a multilayered structure including a polyolefin layer and an EVOH layer. Such a recovery technique is useful from the perspective of the reduction of wastes and the economic efficiency and is employed widely.
However, when reusing a regrind of a multilayered structure including a polyolefin layer and an EVOH layer, gelation occurs due to thermal degradation during the melt molding or a degraded material adheres inside an extruder, and thus it used to be difficult to carry out continuous melt molding for a long period of time. Further, since such a degraded material is often mixed into a molded product, there used to be problems of generating a fish eye and generating a phase separation foreign matter (die build-up) in a molded product thus obtained. In addition, when producing a multilayered structure continuously, uneven cloudiness (partial decrease in transparency) occurs and gets worse, and thus there used to be a problem of worsening supply stability and long run workability.
As a measure to solve such problems, Patent Document 1 describes a multilayered structure having a layer made of a resin composition having an ethylene-vinyl acetate copolymer and a saponified ethylene-vinyl acetate copolymer, having an ethylene content of 70 mol % or more, blended into a regrind of a layered product including a polyolefin-based resin layer and an EVOH layer. It is considered that, in this multilayered structure, a die build-up and discoloration are suppressed to be excellent in appearance. However, in a case of producing a multilayered structure continuously, uneven cloudiness sometimes occurs and gets worse, and thus it sometimes lacks in supply stability and long run workability.